Tubular incandescent lamp



July 13, 1965 w. F. HODGE 3 0 TUBULAR INCANDESCENT LAMP Filed March 17. 1961 lnven tor: WiLLiam E Hod ge b 0% f His Atdro neg United States Patent O 3,195,001 TUBULAR INCANDESCENT LAMP William F. Hodge, Lyndhurst, Ohio, assignor to General Electric Company, a corporation of New York Filed Mar. 17, 1961, Ser. No. 96,531 3 Claims. (Cl. 313-27?) This invention relates generally to electric incandescent lamps, and more particularly to lamps comprising an elongated tubular envelope of vitreous material having a coiled filament wire extending axially thereof and supported in the envelope axis by a plurality of support members engageable with the inner envelope wall.

In the case of certain lamp types the support members are in the form of sheet metal wafers or discs disposed transversely of the filament coil and apertured at the center thereof to engage and support the filament coil between adjacent turns of the coil. In some cases, the construction is such that the wafers are securely fastened to the filament coil. In other cases, the construction is such that rotation of the wafer relative to the filament coil is not effectively prevented. It has been found that in the latter cases vibration of the lamps in shipment or in certain applications can cause rotation of the wafers and resultant advancement or screwing action of the water along the filament coil to an excessive degree such that the spacing between successive discs may become unduly enlarged. The unsupported span of filament coil then becomes so great that the coil, when heated to incandescence, may sag against the envelope wall.

Rather than introducing complications in attempting to achieve a secure anti-turning attachment of the wafers or discs to the filament in all cases, in accordance with the present invention means are provided for locking the wafers against rotation relative to the inner wall of the envelope. Since the filament coil is mounted so that it is not rotatable about its axis relative to the envelope, the wafers are thereby also looked against rotation relative to the filament coil.

For a further understanding of the invention reference is directed to the following detailed description and to the drawing wherein:

FIG. 1 is an elevation of an electric incandescent lamp embodying the invention;

FIG. 2 and FIG. 3 are fragmentary elevations showing portions of different filament coil forms and an associated supporting wafer or disc;

FIG. 4 is a transverse section of the lamp along the line 4-4 in FIG. 1 showing one form of structure for preventing rotation of the supporting wafers relative to the envelope wall; and

FIG. 5 is a view similar to FIG. 4 of another species of structure for preventing rotation of the supporting wafer.

Referring to FIG. 1 of the drawing, the lamp illustrated therein by way of example may be of the infrared or heat lamp type disclosed and claimed in Patent 2,864,025, Foote et al. Such a lamp comprises a sealed gas-filled tubular envelope 1 of essentially circular cross-section and of vitreous material such as quartz. A helically coiled tungsten wire filament 2 extends axially of the envelope 1 and is connected at its end to lead-in conductors 3 which extend outwardly through, and are hermetically sealed in, press or pinch seal portions 5 at the ends of the envelope.

The filament coil 2 is supported and maintained in the axis of the envelope 1 by a series of spaced support members 6. A preferred form of support member 6 is a sheet metal wafer or disc of the type disclosed and claimed in Patent 2,813,993, Fridrich, and formed and attached to the filament coil by the method and apparatus disclosed and claimed in Patent 2,813,327, Fridrich. Each said ice disc 6 is disposed between adjacent turns of the filament coil 2 (FIG. 2) and is provided with a central aperture 7 (FIG. 4) and a radial slit 8 extending therefrom to the periphery of the disc. A portion of the wire in the ad jacent turns of the coil 2 extends through the portion of the slit 8 adjacent to the aperture 7, and a collar portion 9 (FIG. 2) at the margin of the aperture 7 and at the interior of the ,coil 2 engages at least a portion of a coil turn at one side of the disc. The collar 9 is formed by a piercing tool inserted through the interior of the filament coil 2 so that it is of a furcated character comprising a plurality of tongues or tabe's 10 which are ordinarily caused to curl about andfirmly grip the inner side of the adjacent turn of the filament coil 2. However, in some cases, due to unavoidable limitations or specifications in size and shape of the filament coil, the attachment of the .disc 6 to the coil is not sufficiently secure to avoid rotation of the disc relative to the coil when subjected to vibration. In such cases, the disc 6 moves along the coil 2 by a screw action; it may move a distance as great'as the original spacing between discs, or even greater if more than one disc moves. In such cases the unsupported span of the filament coil 2 is so great that it may sag against the wall of the envelope 1 when the coil is heated to incandescence during operation of the lamp.

One of the situations where there may be rotation of the wafer or disc 6 relative to the filament coil 2is that illustrated in FIG. 2 wherein the helically coiled filament has a comparatively large pitch or spacing between turns suchthat the tabs 10 of the collar portion 9 of the wafer do not engage a sufficiently large part of a coil turn to secure a locking grip.

Another such situation is that illustrated in FIG. 3 where the filament 2 is in the form of a double coil consisting of two coaxially arranged coils 2a and 2b. The double coil arrangement is desirable in certain applications to achieve, at a given color temperature, a lamp of relatively long length and high wattage operable at relatively low voltage. In this case, the tabs of the collar portion 9 of the disc 6 engage or grip a portion of a turn of each coil 2a and 2b, and the grip of the collar portion on one or both of the coil turns may become partially loosened if the coils are moved relative to each other. This may occur during manufacture of the lamp while the filament assembly of coil 2, discs 6 and lead-in conductors 3 is being sealed in the envelope 1. During such assembly, one end of the envelope is sealed at the pinch portion 5, after which the filament 2 is stretched to place it in tension by pulling on the lead-in conductor 3 at the other end. It is during such stretching of the filament that the grip of the collar portion of one or more of the discs 6 on one of the coil turns 2:: or 2b may become loosened.

In accordance with the invention, rotation of the wafers or discs 6 with respect to the filament coil is prevented by the provision of means locking said discs against rotation relative to the envelope. In the arrangement shown in FIG. 4, the inner wall of the envelope 1 is provided with a small rib-like key 11 extending longitudinally the full length of the envelope, and each of the discs 6 is provided with a matching notch 12 at its periphery engaging said key 11.

In the arrangement shown in FIG. 5, the locking or keying function is provided by a segmented flat surface 13 interrupting the circular contour of the inner wall of the envelope 1' and extending the full length of the envelope. Each of the discs 6' is provided with a corresponding straight chord-shaped peripheral portion 14 which engages the fiat surface 13 of the envelope to prevent rotation of the disc relative to the envelope. An incidental advantage of this construction is the formation of a plano-convex lens portion 15 whereby some of the radiation from the filament through said lens portion is concentrated in a desired direction, particularly when most of the remainder of the radiation from the lamp is also concentrated through the use of a cooperating reflector indicated at 16. V

In either of the constructions shown in FIGS. 4'and 5, the locking ridge 11 or flat 13- is readily formed during the operation of drawing the quartz tubing 1, and in both cases the wafers .or discs 6 and 6' are effectively locked against rotation relative to the envelope and relative to the filament coil 2 or 2'.

During formation of the disc 6 in the preferred manner described in the aforesaid Patent 2,813,327, the radial slit 8 (FIG. 4) terminates in a V-shaped notch 17 at the periphery of the disc. When desired, the said notch 17 may be employed as the locking element on the disc en gageable with the key 11. However, it is preferred to cut out separate notches 12 after attachment of'the discs 6 and lead-in conductors 3 to the filament coil 2, thereby assuring accurate alignment of the notches 12 in the individual discs for easy threading of thefilarnent assembly into the envelope 1 prior to sealing of the ends 5, and also to position the planes of the foil portions of the lead-in conductors 3, so that the orientation of the pinch seal portions S'will have the desired relationship to the key 11 of FIG. 4 or the flat surface 13 of FIG. 5.

What I claim as new and desire to secure by Letters Patent of the United States is:'

1. In an electric incandescent lamp comprising a tubular envelope of essentially circular cross-section, a helically coiled wire filament extending axially of said envelope, and a plurality of supporting circular Wafer members disposed transversely of and at spaced intervals along said filament and engageable at their peripheries with the inner wall of said envelope, said wafer members being centrally apertured and engaging the filament coil between adjacent turns thereof to support it in the axis of said envelope but being rotatable with respect to said filament coil, said envelope having an integral portion of its inner wall deformed from the circular cross section in an angularly localized zone extending uniformly the length of the envelope, and said water members having at their peripheries angularly localized zones deformed from the circular in matching conformance to the said localized zone of the envelope inner wall whereby to hold said wafers against rotation relative to the inner envelope wall.

2. A lamp as set forth in claim 1 wherein the said means locking said wafer members against rotation relative to the inner Wall .of said envelope comprises a longitudinally extending rib-like key on the inner envelope wall and a notch in each said wafer fitting around said key.

3. A lamp as set forth in claim 1 wherein the said means locking said wafer members against rotation relative to the inner wall of said envelope comprises a segment-shaped flat surface interrupting the circular crossseetion of the inner envelope wall and extending longitudinally of the envelope, and a corresponding chordshaped peripheral portion of each said water engaging v said flat surface of the inner envelope wall.

References Qited by the Examiner UNITED STATES PATENTS 2,813,993 11/57 Fridrich 313274 X 2,910,695 1'1/59 Hodge 313- 275 X 2,943,227 6/60 Levin 3l382 2,980,820 4/61 Brundige et al. 3l3--275 X 3,039,015 6/62 Jolly 313-279 GEORGE N. \VESTBY, Primary Examiner.

ARTHUR GAUSS, Examiner. 

1. IN AN ELECTRIC INCANDESCENT LAMP COMPRISING A TUBULAR ENVELOPE OF ESSENTIALLY CIRCULAR CROSS-SECTION, A HELICALLY COILED WIRE FILAMENT EXTENDING AXIALLY OF SAID ENVELOPE, AND A PLURALITY OF SUPPORTING CIRCULAR WAFER MEMBERS DISPOSED TRANSVERSELY OF AND AT SPACED INTERVALS ALONG SAID FILAMENT AND ENGAGEABLE AT THEIR PERIPHERIES WITH THE INNER WALL OF SAID ENVELOPE, SAID WAFER MEMBERS BEING CENTRALLY APERTURED AND ENGAGING THE FILAMENT COIL BETWEEN ADJACENT TURNS THEREOF TO SUPPORT IT IN THE AXIS OF SAID ENVELOPE BUT BEING ROTATABLE WITH RESPECT TO SAID FILAMENT COIL, SAID ENVELOPE HAVING AN INTEGRAL PORTION OF ITS INNER WALL DEFORMED FROM THE CIRCULAR CROSS SECTION IN AN ANGULARLY LOCALIZED ZONE EXTENDING UNIFORMLY THE LENGTH OF THE ENVELOPE, AND SAID WAFER MEMBERS HAVING AT THEIR PERIPHERIES ANGULARLY LOCALIZED ZONES DEFORMED FROM THE CIRCULAR IN MATCHING CONFORMANCE TO THE SAID LOCALIZED ZONE OF THE ENVELOPE INNER WALL WHEREBY TO HOLD SAID WAFERS AGAINST ROTATION RELATIVE TO THE INNER ENVELOPE WALL. 